1. Field of the Invention
The present invention relates to an absorption chiller-heater and a generator for use in such absorption chiller-heater, and more particularly to an absorption chiller-heater which is driven by an exhaust gas and can effectively utilize a high-temperature exhaust gas discharged from an external apparatus such as a gas turbine to increase exhaust heat utilization efficiency, and to a generator for use in such absorption chiller-heater.
2. Description of the Related Art
There has been known a cogeneration system which performs a cooling operation, a heating operation, and a hot-water supply operation using a high-temperature exhaust gas discharged from an external apparatus such as a gas turbine. In the cogeneration system which incorporates a gas turbine having a small capacity, cases where a hot-water supply operation, a cooling operation, and a heating operation are performed by recovering heat from a high-temperature exhaust gas are increasing. For example, in the cogeneration system which incorporates a micro-gas turbine of the 20 to 100 kW class, heat is recovered from an exhaust gas discharged from the micro-gas turbine and having a temperature of about 200 to 300xc2x0 C. for thereby performing a hot-water supply operation, a cooling operation, and a heating operation. In this case, the high-temperature exhaust gas discharged from the gas turbine is supplied to an exhaust-gas boiler to produce hot water for thereby performing a hot-water supply operation and a heating operation, or to produce hot water for thereby performing a cooling operation by an absorption chiller which uses the produced hot water as a heat source.
However, in the cogeneration system which utilizes such hot water, the apparatus structure is complicated, a thermal efficiency of the absorption chiller-heater is low, and a problem of operational characteristics arises.
The present invention has been made in view of the above drawbacks in the prior art, and it is therefore a first object of the present invention to provide an absorption chiller-heater which is driven by an exhaust gas, can effectively utilize a high-temperature exhaust gas by a simple apparatus structure, and has a high thermal efficiency.
A second object of the present invention is to provide a generator for use in such absorption chiller-heater which can reduce the amount of absorption solution to be reserved by a simple apparatus structure, is free from local superheat and has a high reliability with a compact structure, and can effectively utilize a gas serving as a heat source (heat source gas) by causing the heat source gas and the absorption solution to flow in a countercurrent flow by a simple apparatus structure.
In order to achieve the first object, according to a first aspect of the present invention, there is provided an absorption chiller-heater comprising: an absorber; a low-temperature generator; an exhaust heat recovery generator; a high-temperature generator; a condenser; an evaporator; a solution path and a refrigerant path for connecting the absorber, the low-temperature generator, the exhaust heat recovery generator, the high-temperature generator, the condenser, and the evaporator; and an exhaust gas path for introducing a high-temperature exhaust gas serving as a heat source into the high-temperature generator, and then the exhaust heat recovery generator, the exhaust gas path being substantially straight in a flow direction of the exhaust gas; wherein the high-temperature generator and the exhaust heat recovery generator comprise a vertical heat transfer tube bank for allowing the high-temperature exhaust gas to flow therethrough, a gas-liquid separation chamber is provided above the vertical heat transfer tube bank so as to cover opening portions of the vertical heat transfer tube bank, a solution supply chamber is provided below the vertical heat transfer tube bank so as to cover opening portions of the vertical heat transfer tube bank, and the high-temperature exhaust gas is led to the vertical heat transfer tube bank of the high-temperature generator, and then the vertical heat transfer tube bank of the exhaust heat recovery generator.
The exhaust gas path may comprise an upper tube plate and a lower tube plate for the vertical heat transfer tube bank, and both side plates, and have a rectangular cross section for thereby achieving a desired simple structure.
Further, a heat exchanger for recovering heat from the exhaust gas may be provided between the high-temperature generator and the exhaust heat recovery generator in the exhaust gas path, and/or downstream of the exhaust heat recovery generator in a flow direction of the exhaust gas. Thus, the solution to be introduced into the high-temperature generator can be preheated to utilize the exhaust gas more effectively. The heat exchanger for recovering heat from the exhaust gas may comprise a horizontal heat transfer tube bank provided in the exhaust gas path having a rectangular cross section.
Further, a downcomer may be provided between the gas-liquid separation chamber and the solution supply chamber in the high-temperature generator and the exhaust heat recovery generator to circulate the solution smoothly.
In order to achieve the second object, according to a second aspect of the present invention, there is provided a generator for use in an absorption chiller-heater, comprising: an upper tube plate; a lower tube plate; a vertical heat transfer tube bank provided between the upper tube plate and the lower tube plate, the vertical heat transfer tube bank comprising a plurality of heat transfer tubes for allowing absorption solution to flow therethrough, and a gas serving as a heat source flowing outside of the heat transfer tubes; and a plurality of downcomers provided between the upper tube plate and the lower tube plate for allowing the absorption solution to flow therethrough downwardly.
By providing the downcomers, the solution can be circulated smoothly between the gas-liquid separation chamber and the solution supply chamber to improve heat transfer and prevent local superheat. Further, the downcomer may be provided in the same manner as the vertical heat transfer tube bank, i.e. may be provided in the vertical heat transfer tube bank and between the tube plates, thus making an apparatus structure compact and increasing a reliability of the apparatus.
In the case where the downcomer is provided in the heat transfer tube bank, the downcomer may be thermally isolated from the exhaust gas, or may comprise a double tube so that a downcomer portion does not contact the exhaust gas directly.
The solution reserving section may be composed mainly of the interior of the vertical heat transfer tube bank, the solution supply chamber and the gas-liquid separation chamber, and hence may be reduced extremely.
In order to achieve the second object, according to a third aspect of the present invention, there is provided a generator for use in an absorption chiller-heater, comprising: an upper tube plate; a lower tube plate; a vertical heat transfer tube bank provided between the upper tube plate and the lower tube plate, the vertical heat transfer tube bank comprising a plurality of heat transfer tubes for allowing absorption solution to flow therethrough, and a gas serving as a heat source flowing outside of the heat transfer tubes; a gas-liquid separation chamber provided above the upper tube plate so as to cover opening portions of the vertical heat transfer tube bank; a solution supply chamber provided below the lower tube plate so as to cover opening portions of the vertical heat transfer tube bank; at least one baffle plate provided in each of the gas-liquid separation chamber and the solution supply chamber for dividing the vertical heat transfer tube bank into a plurality of blocks in a flow direction of the gas; an absorption solution inlet for supplying the absorption solution to one of the gas-liquid separation chamber and the solution supply chamber, the absorption solution inlet being provided at an outlet side of the gas; and an absorption solution outlet for discharging the absorption solution from the gas-liquid separation chamber, the absorption solution outlet being provided at an inlet side of the gas.
By combination of the block structure formed by the baffle plate and the downcomer, the solution can be smoothly circulated up and down and the whole flow of the solution can be regulated. Further, the solution and the exhaust gas flow in a countercurrent flow to increase the temperature difference for heat transfer, thus utilizing the exhaust gas effectively.
In order to achieve the second object, according to a fourth aspect of the present invention, there is provided a generator for use in an absorption chiller-heater, comprising: an upper tube plate; a lower tube plate; a vertical heat transfer tube bank provided between the upper tube plate and the lower tube plate, the vertical heat transfer tube bank comprising a plurality of heat transfer tubes for allowing absorption solution to flow therethrough, and a gas serving as a heat source flowing outside of the heat transfer tubes; wherein the upper tube plate comprises an integral component, and an upper chamber is provided above the upper tube plate so as to cover the upper tube plate; the lower tube plate comprises an integral component, and a lower chamber is provided below the lower tube plate so as to cover the lower tube plate; both sides of the vertical heat transfer tube bank are covered by flat plates which connect the upper chamber and the lower chamber; and the upper tube plate, the lower tube plate and the flat plates define a gas flow path for allowing the gas to flow therethrough.
According to the present invention, there is no liquid-cooled wall at both sides, and the solution reserving section is composed mainly of the interior of the vertical heat transfer tube bank, the upper chamber and the lower chamber, and hence the amount of the solution to be reserved can be reduced extremely. In the generator according to the fourth aspect of the present invention, a downcomer may be provided to connect the upper chamber and the lower chamber. Further, a baffle plate for regulating the flow of the solution may be provided to allow the gas and the solution to flow in a countercurrent flow.
The above and other objects, features, and advantages of the present invention will be apparent from the following description when taken in conjunction with the accompanying drawings which illustrates preferred embodiments of the present invention by way of example.